What do you do if someone is attacked with corrosive liquid?

Over 100 Islington business owners and employees found out at a dramatic training session on Wednesday.

The training, Project Diffuse, was organised by the Angel Business Improvement District and delivered by police officers at Islington Metal Works in Torrens Street.

It was standard enough to begin with. Counter terrorism officer Neil Parham was discussing the recent high profile corrosive attacks – using substances like acid – in the past year.

Then someone screamed in agony.

A woman fell to the floor and security rushed in from the back of the room.

Dozens of other people began screaming. They had garish injuries to their necks and faces.

The audience was ushered into the courtyard, where door staff poured copious amounts of water on the victim’s wounds.

About 10 minutes later, the “emergency services” arrived.

This, of course, was a mock emergency, with the injuries created by a make-up artist. It was designed to replicate an attack on revellers in a nightclub – much like the one Arthur Collins delivered in Dalston last Easter.

If Pc Parham had one message for his audience to take away from the drill, it was this: “Access to water is the key.

“It’s going to be chaos. The police aren’t here. You are the first responders on the scene. You are on your own for the first eight minutes.

“The beginning of a response to an acid attack doesn’t start with the fire brigade or police or ambulance service. It starts with you. In a corrosive attack the effects are immediate and how you deal with it can have life changing effects.”

Water, he explained, is vital because it flushes away and dilutes the corrosive liquid that reacts with fat tissues under the skin.

Having said that, it must be done correctly.

“When applying water,” Pc Parham explained, “we need to think of a run off we need to make sure the water is running down and not onto other parts of the victim’s body.

“Victims will be volatile, hostile and emotional, but we need to try and keep them calm and under control.”

Last year, there were seven corrosive attacks in Islington, including one in Copenhagen Street near the Barnsbury Estate in April and another in St Paul’s Road, Highbury, in July.

But Mike West, a Met Police expert in corrosive attacks, was keen to point out: “These attacks represent 0.2 per cent of violent crimes in London. The Met is treating this a seriously as knife or gun crime and we are seeing promising signs of a reduction in these attacks.

“Month on month, there’s been fewer incidents since July 2017, with last month being the lowest since May 2014.”